Using Apple Watch while swimming
Does the heart rate monitor disconnect while swimming or inside water? Every time I swim (open sea) the watch stops registering the heart rate
Apple Watch Series 2, watchOS 5
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There are several likely problems for heart rate monitoring during swimming. First, the water between the watch’s optical sensor and your arm will have different characteristics rather than the air for which the sensor was designed.
Second, your arm movements are probably fairly energetic and unless the fit of the watch band is perfect the watch will tend to move on your arm so the readings are noisy and unreliable.
Third, open water swim is typically a cold-ish water, and the natural physiological response is to reduce surface blood flow and conserve heat. The watch relies on surface blood flow for its measurements.